Emergency damper control



Oct 1954 B. E. COLBURN ET AL EMERGENCY DAMPER CONTROL Filed June 2, 194950 5 9M3. M U a 2 m 0 a v J 5 Snnentors 55mm. 5. Ca; as

4. Co "a wew/ (Ittorneg s Patented Oct. 26, 1954 UNHTED STATES PATENTOFFICE Bear! E. Colburn and Lee Colburn, Green Bay, Wis.

Application June 2, 1949, Serial No. 96,795

12 Claims. 1

Our invention relates to improvements in emergency damper controls.

Heating devices, such as furnaces and other fuel burning units relyingupon air supply and the adjustment of quantity of air supply for theircontrol, even though provided with automatic devices for the adjustmentof dampers, check drafts, and draft doors, ofier a distinct fire hazardin the event that the operator forgets to retard the fire, or in theevent that the automatic device fails, for lack of power, or fails dueto mechanical disability. It is the object of our invention to providean emergency control, supplemental to either a hand-operated orautomatically-operated air feed control for furnaces or heaters,whereby, in the event of an overrun of temperature, to shut off air feedor otherwise to check combustion.

More specifically stated, it is the object of our invention to provide athermostatically responsive device which will assure return of damper,draft doors, or checks to fire retarding position if temperature exceedsa safe control value.

Another object of our invention is to provide a thermostaticallyreleasable emergency link for a conventional control of a furnace draft.

In the drawings:

Fig. 1 is a perspective of our emergency draft damper control, showingour emergency releasable strip chain in normal, or standby position, inreadiness for an emergency release.

Fig. 2 is a side elevation of a conventional Warm air furnace with ourcontrol in position for draft door release.

Fig. 3 shows our invention installed on a conventional warm air furnacein position for check damper release.

Fig. 4. is a longitudinal vertical section through our emergencycontrol.

Fig. 5 is a section on line 55 of Fig. 4.

Fig. 6 is a section on line 6-6 of Fig. 5.

Fig. 7 is a detail of our emergency trip chain and illustrating its modeof releasable attachment to the. operating arm of our control.

Like parts are designated by the same reference character throughout theseveral views.

Conventionally, draft doors ill for furnaces H, and check dampers i2 forsuch furnaces are controlled by control chains !3 in a well-knownmanner, either by connection to manually operated devices, or toautomatically controlled devices which raise and lower the chains toalter the position of a draft or check.

Draft door It) or check damper l2 will either close of its own weight,as shown in Fig. 2, or a special weight, as shown at M may be used toassure that the damper will assume a safe position if the chain i3 isreleased. If, however, due to power failure of an automatic dampercontrol device or to forgetfulness of the operator of a manuallycontrolled furnace, the damper or check is left in position for rapidcombustion of fuel in the furnace, a dangerous condition may develop.We, therefore, provide our emergency draft damper control now to bedescribed.

Our draft damper control includes an instrument housing l5 on a backplate 16 which may be secured by suitable sheet metal screws orotherwise to the casing of a furnace l I as shown clearly in Figures 2and 3. Extending forwardly from a side wall of the instrument housing[5, is a free floating lever ll which may oscillate freely about theshank I 8 of a slotted thimble l9 mounted in a boss 20 forming a part ofthe side wall of the housing I5. Control chain [3 is connected near theouter end of lever I! and we provide a control chain from the lever l!to the damper ID or check l2.

At 26 the arm I! is provided with a spool apertured at 21 to freelyreceive a special, bead type trip chain 28. This forms an emergency linkbetween the chain 25 and a release ring receivable in slotted thimble[9. So long as the release ring is held in the slot in the thimble l9,chain l3 and the chain 25 act as one continuous pull chain element sothat the automatic or manual device used to adjust these chains and theposition of the dampers to which they are connected will besubstantially in accord with conventional practice. Dampers and draftdoors are often quite heavy, and it is for this reason that we providepin 29 projecting from arm I! at a point spaced from the spool andsomewhat below a straight line drawn between the trip rod and the spool.Release of the ring 30 under emergency conditions and the use of pin 29will be described below.

When the ring is released, the weighted damper pulling downwardly uponchain 25 will pull the free running trip chain 28 through spool 26 untilthe ring 36 strikes the spool. This will in effect add some chain to theeffective length of the chain 25 and permit the damper or check toclose.

Extending rearwardly from the back plate [6 into the bonnet of furnace His a thermostatic device including a mounting tube 3|, a helically woundoi-metallic element 32 and a thermostatically controlled rod 33 whichextends centrally of the tube 3| into the instrument housing l where theend of the thermostatically controlled rod 3| is provided with a tripflange 34. Tube 3i is guided in collar 35 welded or otherwise secured tothe back plate it, and the tube may be oscillated in the collar by meansof a temperature setting lever 36, which is rigidly secured to a tubecollar 3'! fixed upon inner end of the tube 3! as shown clearly inFigures 1, 4 and 5. Temperature setting lever 58 extends through the topof the instrument housing l5 and is disposed in front of calibrationsmarked on the back plate and will therefore indicate the temperaturesetting of thermostat 32, since one end of the bi-metal helix is securedto the tube at 38 and the other end of the helix is secured at 39 to rod33.

It will be clear from this description that upon movement of thetemperature setting lever 36 the tube 3| is oscillated so as to changethe position of the point of attachment of the helix 32 at 38. Thispoint of attachment is the reference point from which the helix operatesand therefore determines the temperature at which our emergency controlis to operate.

In Figure 6 it will be noted that slot 4!} extends substantially beyondthe axis of shank l8 of the thimble and that the shank it is bored at 4|to loosely receive trip rod 42, which extends retractably transverselyof the slot 40 and transversely of the interior of the instrument case.The trip rod is provided with a shoulder flange 43 and a knurledextension 44 to protrude from the instrument case on the side oppositthimble i9. Reset spring 45 between the side of the instrument case andthe shoulder flange 43 of trip rod 42 constantly urges the trip rodtoward the left as seen in Figures 5 and 6.

Extending from collar 34 on rod 33 is a trip lever 46, which is inposition to oscillate against shoulder flange 43 of trip rod 42 inopposition to the thrust of spring 45 when the temperature ofthermostatic element 32 increases so as to provide increased torque.

When trip lever 46 does not interfere, spring 45 thrusts rod 42 intoposition across the slot 44 so that it may extend through release ring30 and retain it in position during normal operation of the furnace.

It will now be clear that so long as the trip rod 42 is in position toretain the release ring 30 the furnace controls applied to chain leverl? and chain will operate in the conventional manner to raise and lowerchain 13 to open and close any drafts or dampers connected thereto.Throughout such normal operation the arm ll will oscillate freelywithout aifecting any of the mechanism in the instrument housing [-5,and release ring will oscillate freely about the trip rod 42.

If, however, the temperature of the thermostatic element 32 whichextends into the bonnet of the furnace II, exceeds the temperature forwhich arm 36 has been set, the trip lever 45 oscillated by thethermostatic action upon helix 32 and rod 33 will bear against shoulder43 to compress spring 45 and retract trip rod 42 from slot 40. When thisoccurs, release ring 35} is released by trip rod 42 and the freelyrunning bead chain 28 will slip through spool 26 so as to add a numberof inches to the efiective length of chains 25 and is, thus permittingthe damper or check to close of its own weight.

To set our emergency draft damper control the release ring and the chain28 may be manually pulled back into the position shown in Figures 1,

5, and I, while the knurled reset extension 44 is pulled outwardly ofthe house 15, against the compression of spring 45. Then while therelease ring is held in position, the trip rod 42 will be permitted toassume the position in Figure 5 under the thrust of spring 45. Obviouslythis cannot be done while the trip lever 46 is in a position dictated bya high temperature in the furnace bonnet, but will ordinarily be doneafter the fire in the furnace has been damped by our emergency releaseof the chain 28.

It will be noted that we have made provision for adjustment of thecritical release point of our control, since arm 38 and tube 3| to whichit is attached constitute the reference point from which the helix 32operates. If there is need to recalibrate the thermostatic device, weprovide a screw at 47 through collar 3? to bear against the tube 3!.This set screw may be released and a different setting of the collar 37and arm 36 with reference to the tube may b determined. Then when theset screw 41 is again tightened a new reference point for the thermostat32 will have been obtained and the temperature setting at which the triparm 46 will effectively withdraw the trip rod 42 can be accurately setby moving the temperature setting lever 36.

Obviously chain arrangements between our emergency draft damper controland the actual draft door l0 may be direct as shown in Figure 2, or itmay follow devious paths over pulleys 47, 48, to check l2 as shown inFigure 3.

We referred above to the fact that a heavy draft door might causetrouble in the operation of the release ring 30. Since friction inducedbe tween rod 42 and the ring may be considerable, pin 29 is sopositioned that trip chain 28 may be drawn beneath it and the pin willthen be disposed between two of the beak like links. The personresetting our emergency damper control can pull the trip chain farenough toward the trip rod 42 so that some slack may be provided in thelength of trip chain extending from pin 29 to the release ring 30. Infact, then, the trip chain is snubbed around the pin 29 and will remainin this position to take some of the strain off of the slack and of thetrip chain, thus reducing the friction between trip rod 42 and the ring30 when an emergency release trip operation is to be accomplished.

In the operation the release ring is held firmly in the slot 40 by thetrip rod 42, until the temperature of the bimetallic helix 32 is raisedto the critical degree to which the temperature setting lever 36 hasbeen set. As the temperature increases the trip lever 46 is oscillatedto the right (counterclockwise) as seen in Fig. 5, and the trip rod 42is thrust to the right against the pressure of spring 45. Finally thering 30 is released by the trip rod so that the trip chain 28 slidesthrough spool 26. Thus, when the ring 30 strikes the spool the length ofthe trip chain 28 has been added to the controlled chain 25 and this issufiicient to permit the damper Ill or check l2 to close.

When the fire has been damped sufficiently to cool the thermalresponsive helix 32 our emergency damper control may be manually reset.The trip lever will have moved clockwise to a position permitting thespring to thrust trip rod 42 to the left (Fig. 5), and the trip rod canbe with drawn to the right, manually, while ring 30 is inserted in theslot 40. Trip rod 42 may then be manually released, to be "laced throughthe ring. Our emergency damper control is then set for an automaticrelease, should an emergency hi temperature condition again be reached.

From the above description it will be seen that our emergency draftdamper control provides an effective release of an emergency trip chain28 in chains l325 to shut down furnace operation in the event thatexcessive temperatures develop in a furnace. Many of the automaticfurnace controls now on the market are equipped with thermostaticdevices known as limit controls by means of which it may bepredetermined that the automatic temperature control of the furnace willshut down the furnace drafts or other combustion promoting means at apredetermined high temperature. Such predetermined high temperaturemight be 300 degrees in the bonnet of the furnace l l, and our emergencydraft control thermostat 32 would then be set at a somewhat highertemperature, as for instance, 325 degrees. If the furnace temperaturethen exceeded the normal 300 degree limit, this indicating that theordinary automatic control had failed, the trip lever 46 would, at 325degrees, withdraw the trip rod 42 and release ring 30 for an emergencyshut down of the dampers.

We claim:

1. In a device of the character described a swingable member having afixed pivotal mounting and a floating end, a pair of control linkagemembers extending respectively to and from the floating end of saidmember whereby to additively provide control linkage of a normal controllength, emergency linkage disposed in releasably retained positionparallel to the swingable member and connected to one of said pair ofcontrol linkage members whereby upon release of the emergency linkageits length is added to said normal control length.

2. The device of claim 1 wherein the swingable member is provided withan apertured spool at its floating end through which the emergencylinkage is freely movable and one end of the emergency linkage isprovided with a release ring too large to pass through the spool.

3. An emergency damper control having a housing providing bearings for apair of rods'disposed at right angles to each other; one of the rodshaving a thermally responsive member for oscillation of the rod and theother rod being a shouldered trip rod reciprocable in its bearings; abearing for one end of the trip rod comprising a shanked and slottedthimble; an arm freely rotatable on the shank of the thimble andprovided with a control chain to move the arm; a spool on the arm spacedfrom the thimble; a controlled chain disposed over the spool andprovided with a release ring disposable in the slot in the thimblewhereby to be releasably retained by the trip rod; and a trip armconnected to the thermally responsive rod in position to bear upon thetrip rod and withdraw it from the release I'll'lg'.

4. An emergency damper control having a housing providing bearings for apair of rods disposed at right angles to each other; one of the rodshaving a thermally responsive member for oscillation of the rod and theother rod being a shouldered trip rod reciprocable in its bearings; abearing for one end of the trip rod comprising a shanked and slottedthimble; an arm freely rotatable on the shank of the thimble andprovided with a control chain to move the arm; a spool on the arm spacedfrom the thimble; a controlled chain disposed over the spool andprovided with a release ring disposable in the slot in the thimblewhereby to be releasably retained by the trip' rod; a trip arm connectedto the thermally responsive rod in position to bear upon the trip rodand withdraw it from the release ring; and a spring between the housingand the shoulder on the trip rod to urge said rod to ring retainingposition.

5. A damper control connection extending from a damper to a point ofcontrol, a movable member at the point of control provided withreleasable attaching means attached to the damper control connection, aspool on the movable member spaced from the releasable attaching meansover which spool the damper control connection may move when releasedand a snubbing pin fixed to said movable member and about which the saidcontrol connection is snubbed between the spool and the releasableattaching means.

6. A damper control connection extending from a damper to a point ofcontrol, a movable member at the point of control, said movable mem berbeing provided with a fixed pivotal mounting, releasable attaching meansadjacent said pivot and to which the damper control connection isreleasably attached, a spool on the movable member spaced from thereleasable attaching means and over which spool the damper controlconnection may move when released and a snubbing pin for said controlconnection between the spool and the releasable attaching means andthermostatic means having a trip for releasing the releasable attachingmeans.

'7. In a device of a character described, a supporting housing providedwith a slotted thimble having a bored shank, a trip rod reciprocable inthe bore in said shank and extending across the slot, a thermostaticallyresponsive member positioned to bear against the trip rod, and a dampercontrol trip chain having a release ring receivable in the slot forengagement by the trip rod, a free floating lever mounted upon the shankof the thimble, and a spool on the lever mounted at a point spaced fromthe trip rod for passage of the trip chain and retention of the ring.

8. A swingable emergency control arm for a two-part tension connectionfor a damper, said arm being swingable about a fixed center, one of saidparts of the tension connection being directly connected to a swingableoutlying portion of said arm, the other of said parts being releasablyconnected adjacent the center and held approximately parallel to the armby a pulley-like spool adjacent said outlying portion of the arm, and athermally responsive tripping device adjacent said center to releasesaid other part of the twopart connection whereby to lengthen thetension connection.

9. The control of claim 8 wherein the spool is shaped to retain thereleased end of said other part.

10. An emergency damper control comprising a support, thermallresponsive trigger mechanism mounted on said support, an arm pivotallyconnected to said support, portions of the arm remote from the pivotbeing provided with connections for control linkages to a damper andconnections for control linkages to a damper control, said controllinkages being in series and said arm being normally oscillatable aboutits pivot Without materially altering the combined lengths of the saidcontrol linkages, one of said control linkage connections comprising anapertured spool on the arm, and a releasable coupling connected withsaid trigger mechanism and to which coupling one of said controllinkages is attached;v said one control linkage extending to saidcoupling through said spool aperture and along said arm, the thermalresponse of said trigger mechanism being effective to release thecoupling and said one control linkage for movement along the arm wherebyto increase the effective combined length of said linkages.

11. The device of claim 10 wherein said one linkage has a stop portionengageable with said spool whereby to limit the increase of the com- 10bined lengths of said control linkages upon actuation of the triggermechanism.

12. The device of claim 11 wherein said thermally responsive triggermechanism comprises members mounted for relative movement and thermallyresponsive means for causing such relative movement, one of said membershaving 87 motion transmitting connection with said releasablecouplingand the other of said members being provided with means foradjusting said mechanismto be responsive to a selected temperature.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 552,924 Reynolds Jan. 14, 1896 1,966,724 Kimball July 17, 19342,190,892 Swepston Feb. 20, 1940 2,240,763 Dillman May 6, 1941 2,249,886Dayton July 22, 1941 2,284,082 Bloch May 26, 1942 2,302,108 De LanceyNov. 17, 1942

